1. Field of the Invention
The present invention relates generally to a construction in which a name plate is mounted to an operating knob for operating a switch and, more particularly, to a knob construction suitable for a lighted switch having a light source within the knob.
2. Description of the Related Art
A conventional knob construction for a lighted switch is disclosed, for example, in Japanese Utility Model Publication No. 63-101423. With this construction, a knob is formed with a recess in its surface surrounding the lighting window, and a name plate of a translucent resin material is fixedly mounted by a double-sided adhesive tape.
However, the conventional construction is disadvantageous in that the adhesion of the tape decreases due to changes in environmental conditions such as temperature and humidity, and the name plate is therefore apt to come off the knob. The adhesion of the tape also varies depending on the level of soiling and surface roughness of the name plate and/or of the knob on which the name plate is bonded. Thus, reliable bonding of the name plate is difficult.
Moreover, the double-sided adhesive tape is first bonded to either the knob or the name plate and then they are subsequently placed together for bonding. This is not efficient in manufacturing the knob assembly.
Also, if the knob includes a lighted switch therein, the light exiting the window passes through the adhesive layer applied to the back side of the name plate. The adhesive layer attracts dust and other foreign matter. The dust and foreign matter deposited on the adhesive layer are detrimental to the uniform lighting and reduce the amount of light that emanates from the name plate.